Device for administering a fluid

ABSTRACT

A device for administering a fluid is provided, with
     a cylinder ( 16, 116 ) which has an open dispensing end ( 17 ),   a piston ( 36 ) which is displaceable between a front and rear end position in the cylinder ( 16, 116 ) and is connected to a piston rod ( 35 ) that protrudes along a first direction beyond a rear end of the cylinder ( 16, 116 ) opposite the open dispensing end ( 17 ) and is guided in a receiving block ( 10 ),   a nonreturn valve ( 18 ) closing the open dispensing end ( 17 ),   and a tensioning device (S) which is connected to the piston rod ( 35, 135 ) and is arranged in the receiving block ( 10 ),   wherein the tensioning device (S), when the piston ( 36 ) is in its front end position, can move the piston rod ( 35, 135 ) in a tensioning operation along the first direction until the piston ( 36 ) is in its rear end position in order thereby to fill the cylinder ( 16, 116 ) with the fluid to be administered and in order to pretension the piston rod ( 35, 135 ) toward the open dispensing end ( 17 ), and   wherein the tensioning device (S), when the piston ( 36 ) is in its rear end position, can release the piston rod ( 35, 135 ) in a dispensing operation, and therefore the piston ( 36 ) moves counter to the first direction as far as its front end position because of the applied pretension and, in the process, fluid in the cylinder ( 16, 116 ) is dispensed via the nonreturn valve ( 18 ) for administering,   wherein the cylinder ( 16, 116 ) together with the nonreturn valve ( 18 ) is in the form of an exchangeable front assembly ( 13, 14 ) which is releasably connected to the receiving block ( 10 ).

The present invention relates to a device for administering a fluid,which device can be in the form of, for example, a self-filling syringewithout a needle, with which a liquid drug can be administered toanimals.

Such devices for administering a fluid are intended to be as lightweightas possible, to have a long service life and to be associated with lowmaintenance costs and outlay.

It is the object of the invention to provide a device for administeringa fluid that realizes at least one of the properties mentioned.

The invention is defined in claim 1. Advantageous refinements arespecified in the dependent claims.

The device according to the invention for administering a fluidcomprises a cylinder which has an open dispensing end, a piston which isdisplaceable between a front and a rear end position in the cylinder andis connected to a piston rod that protrudes along a first directionbeyond a rear end of the cylinder opposite the open dispensing end andis guided in a receiving block, a nonreturn valve (or intake valve)closing the open dispensing end, and a tensioning device which isconnected to the piston rod and is arranged in the receiving block. Thetensioning device can move the piston rod in a tensioning operation,when the piston is in its front end position, along the first directionuntil the piston is in its rear end position, in order thereby to fillthe cylinder with the fluid to be administered and in order topretension the piston rod toward the open dispensing end. Furthermore,the tensioning device, when the piston is in its rear end position, canrelease the piston rod in a dispensing operation, and therefore thepiston moves counter to the first direction as far as its front endposition because of the applied pretension and, in the process, thefluid in the cylinder is dispensed via the nonreturn valve foradministering. According to the invention, the cylinder together withthe nonreturn valve can be in the form of an exchangeable frontassembly, which may also be referred to as an exchangeable assembly,which is releasably connected to the receiving block.

The entire front assembly which is subject to the greatest amount ofwear during the operation of the device for administering a fluid(preferably a liquid) can then be changed into a new (preferablystructurally identical) front assembly which is then connected to thereceiving block. The durability of the entire device for administering afluid is therefore significantly increased.

The exchangeable assembly can be arranged at the front end of the deviceaccording to the invention. In particular, for example, during correctuse of the device according to the invention part of the exchangeableassembly can be in contact with the animal to which the fluid isintended to be administered. In this respect, at least this part of theexchangeable assembly protrudes from the rest of the device according tothe invention. The exchangeable assembly can have a part which forms thedistal end of the device according to the invention, and therefore, forexample, for this reason the exchangeable assembly may also be referredto as an exchangeable front assembly.

An exchangeable front assembly is understood here as meaning inparticular that the front assembly as a whole can be separated from thereceiving block and replaced by a structurally identical front assemblywhich is connected for exchange to the receiving block. However, it isalso possible for the front assembly which is separated from thereceiving block to be maintained (by, for example, worn parts, such asseals, being exchanged) and then being connected again to the receivingblock.

Since the front assembly is completely separated from the receivingblock and is then maintained or exchanged, undesirable contaminationscan be reliably avoided. This is significantly more difficult andassociated with higher costs if, for example, only the firstly wearingO-ring seals in the front assembly are exchanged individually when thefront assembly, as previously customary, is installed in such a mannerthat it cannot be separated from the rest of the administering devicewithout being destroyed.

The releasable connection between the front assembly and the receivingblock can be in particular a screw connection. However, any other typeof releasable connection, such as, for example, a bayonet connection, isalso possible.

The administering device according to the invention can have a nozzlefor administering the fluid without a needle, said nozzle beingconnected via the nonreturn valve to the open dispensing end of thecylinder and being part of the front assembly. It is therefore possiblefor the nozzle also to be exchanged at the same time as the frontassembly is exchanged.

Alternatively, the device can have a needle or canula which is connectedvia the nonreturn valve to the open dispensing end of the cylinder andis part of the front assembly. The needle and the canula may for theirpart be exchangeable.

The administering device according to the invention can have preciselyone cylinder with precisely one piston rod and precisely one frontassembly. However, it is also possible for the administering device tohave two or more cylinders with two or more piston rods and two or morefront assemblies that are all designed identically, and therefore two ormore identical or different fluids can be admitted simultaneously. Theindividual cylinders can have identical or different volume.

The administering device according to the invention is in particular inthe form of a self-filling administering device which uses thetensioning operation to enable the cylinder to be filled with the fluidto be administered (for example a liquid to be administered).

This can be realized, for example, in such a manner that filling of thecylinder already takes place during the entire tensioning operation.Alternatively, the administering device can be designed in such a mannerthat, during the tensioning operation, a negative pressure is built upin the cylinder, said negative pressure then being used, when the pistonis in its rear end position, for the fluid to be sucked into thecylinder because of the negative pressure. For this purpose, forexample, the distal end of the piston can have a blind hole whichextends in the longitudinal direction of the piston rod and from whichone or more radial bores branch off, the radial bores, in the rear endposition of the piston, producing a fluid connection to a reservoir ofthe fluid to be administered.

The administering device according to the invention can have the motorwhich is used for carrying out the tensioning operation. It may also bestated that the motor provides the energy necessary for building up thepretensioning of the piston rod. The motor can be mounted in particularon the receiving block.

In order to operate the motor and possible further consumers, the energysource provided can be, for example, a battery and/or a storage battery.The energy source can be formed, for example, in the base or as the baseof the administering device. Furthermore, the energy source can beexchangeable or fixedly installed.

The tensioning device can have a spring which pretensions the piston rodtoward the open dispensing end when the piston is in the rear endposition.

The administering device according to the invention can furthermore havea ramp which is rotatable by means of the motor and has a ramp trackextending along a helical line. The ramp track can ascend from a firstplateau or level along a region of inclination to a second plateau orsecond level and can descend from the second plateau to the firstplateau via a transition flank. The ramp track therefore has a singleturn and may be referred to as being helical with a step.

The tensioning device can furthermore comprise a roller which is incontact with the ramp track and is mounted rotatably in a driver, whichis connected to that end of the piston rod which protrudes out of thecylinder, and therefore, upon rotation of the ramp, the ramp track runsbelow the roller, which thereby rotates. The roller is preferablymounted in such a manner that its axis of rotation is perpendicular tothe first direction (or perpendicular to the longitudinal axis of thepiston rod).

For the tensioning operation, the ramp track, starting from contact ofthe roller with the first plateau, can be rotated in such a manner thatthe roller runs on the region of inclination as far as the secondplateau and the piston is thereby moved into its rear end position. Forthe dispensing operation, the ramp track, starting from a contact of theroller with the second plateau, can be rotated until the roller via thetransition flank reaches the first plateau and the piston is therebymoved into its front end position.

The distance of the second plateau from the first plateau along the axisof rotation of the ramp preferably corresponds to the distance from thefront to the rear end position of the piston along the first directionand therefore to the piston stroke.

The rotational movement of the motor is therefore converted by means ofthe ramp and the roller into a translatory movement of the piston rodalong its longitudinal axis. The administering device can therefore betensioned by means of the motor, and therefore a user merely has toactuate a triggering element, for example a pushbutton, a switch, arocker switch or a button, in order to release the dispensing operationand therefore to administer the fluid. It is therefore possible, forexample, for many animals to be rapidly injected one after another withmedication.

The region of inclination of the ramp track can have a first portionadjoining the first plateau and an adjoining second portion, wherein theinclination of the second portion is greater than the inclination of thefirst portion.

The effect is therefore advantageously achieved that, at the beginningof the tensioning operation, the ramp track has a smaller inclination,as a result of which the motor has to apply less force or torque. Thisis advantageous during the starting of the motor since more current isused during the starting. As soon as the first portion merges into thesecond portion, said starting problem has been overcome, and therefore agreater inclination can easily be realized here. This increases thedurability of the motor.

The region of inclination of the ramp track can be designed in such amanner that both portions are linear with respect to the angle ofrotation of the screw. However, it is also possible for the firstportion and/or the second portion to have a nonlinear profile withrespect to the angle of rotation. In this case, the inclination of therespective portion is preferably the average inclination of therespective portion. The nonlinear profile of the respective portion ispreferably a profile in which the local inclination increases as theangle of rotation increases. The nonlinear profile of the respectiveportion can preferably be a concave curvature profile.

In particular, the rotational angle region (or the length of the angleof rotation) of the first portion can be smaller than the rotationalangle region (or the length of the angle of rotation) of the secondportion. The ratio of the rotational angle region of the first portionto the rotational angle region of the second portion is preferably nomore than 4/6 and not less than 1/9.

In the case of the administering device according to the invention, theroller can have a support region which rests on the region ofinclination of the ramp track, and at least one laterally adjoining sideregion which has a smaller outside diameter than that of the supportregion and which does not rest on the region of inclination of the ramptrack. During the dispensing operation, both the support region and theside region can come into contact with an edge of the ramp track, saidedge connecting the second plateau to the transition flank. This leadsto the advantage of there being a relatively low rolling or frictionalresistance between the roller and the ramp track in the region of theregion of inclination. During the transfer via the edge for thedispensing operation, both the receiving region and the side region thenrest on the edge, and therefore the support surface is enlarged here,and thus a smaller pressure is present. This is advantageous since,during the transfer of the roller via the edge, the greatest force actson the roller, and therefore undesirable pressure peaks can be reduced.The durability of the roller is therefore increased.

In particular, the roller on either side of the support region can havea laterally adjoining side region with a smaller outside diameter thanthat of the support region. This leads to a further reduction of thepressure on the roller during the transfer via the edge.

The roller can be designed in such a manner that the outside diameter ofthe support region is constant. The outside diameter of the respectiveside region can decrease in a direction toward the side of the roller(or in a direction away from the support region or as the distance fromthe support region becomes greater).

The roller can be in the form of a plastics roller. The ramp can becomposed of metal.

In the case of the administering device according to the invention, thereceiving block can be in the form of an integral receiving block whichis produced by an additive production method.

Such an additive production method may also be referred to as 3Dprinting and may be, for example, a laser sintering method.

This leads to the receiving block being able to be produced with arelatively low weight and high rigidity and strength. The overall weightof the administering device is therefore kept as low as possible, thusmaking the operation thereof for a user agreeable and durable.

Furthermore, the integral formation of the receiving block by means ofthe additive production method leads in an advantageous manner to itbeing possible for the receiving block to be formed extremely compactly,which is not possible with conventional machining production methods.

The material used for the receiving block is preferably a metal (or ametal alloy) and in particular titanium, and therefore the receivingblock is composed of metal (or a metal alloy) and in particular oftitanium. Furthermore, aluminum, steel (for example maraging steel),stainless steel, titanium, a nickel alloy and/or a cobalt chromium alloycan be used as material for the receiving block. Further possiblematerials are AlSiMg alloys, CoCrMo alloys and nickel chromium alloys.Furthermore, materials which are weldable can be used. All of thesematerials can be present in a form (for example as powder) in order toable to produce the receiving block from them by means of an additiveproduction method (and in particular by means of the laser sintering).

The receiving block can have a motor bearing, a guide cylinder for thepiston rod, at least one receptacle for a control board, a receptaclefor a fluid connection for a fluid container and/or at least one housingfixing point, which is/are formed integrally with the receiving block.

The piston can be formed integrally with the piston rod. In this case,the front end of the piston rod forms the piston. However, it is alsopossible for the piston to be a separate element that is connected tothe piston rod.

It goes without saying that the features mentioned above and those whichhave yet to be explained below are usable not only in the statedcombinations, but also in other combinations or by themselves withoutdeparting from the scope of the present invention.

The invention will be explained in more detail below using exemplaryembodiments with reference to the attached drawings which likewisedisclose features essential to the invention. These exemplaryembodiments serve merely for illustrative purposes and should beinterpreted as restrictive. For example, a description of an exemplaryembodiment with a multiplicity of elements or components should not beinterpreted to the effect that all of said elements or components arenecessary for implementation purposes. On the contrary, other exemplaryembodiments may also contain alternative elements and components, fewerelements or components or additional elements or components. Elements orcomponents of various exemplary embodiments may be combined with oneanother, unless stated otherwise. Modifications and alterations that aredescribed for one of the exemplary embodiments may also be applied toother exemplary embodiments. In order to avoid repetitions, identical ormutually corresponding elements in the various figures are denoted bythe same reference signs and will not be explained repeatedly. In thefigures:

FIG. 1 shows a perspective view of an exemplary embodiment of theadministering device 1 according to the invention;

FIG. 2 shows a schematic sectional view of the administering device 1from FIG. 1;

FIG. 3 shows a schematic, enlarged sectional view of the first frontassembly 13;

FIG. 4 shows a schematic sectional view of the first front assembly 13and of the distal end 30 of the receiving block 10 in a state notconnected to each other;

FIG. 5 shows a schematic sectional view of the first front assembly 13screwed into the distal end of the receiving block 10, with the piston36 being in its rear end position;

FIG. 6 shows a sectional view according to FIG. 5, wherein the piston 36is in its front end position and the triggering cage 21 is in itsrelease position for the administering operation;

FIG. 7 shows a perspective illustration of the receiving block 10together with the tensioning device S, wherein the tensioning device Sis in the basic position in which the piston 36 is in its front endposition;

FIG. 8 shows a perspective illustration of the receiving block 10together with the tensioning device S according to FIG. 7, wherein thetensioning device S is in its tensioned position in which the piston 36is in its rear end position;

FIG. 9 shows a sectional view of the receiving block 10 together withthe tensioning device S according to FIG. 8;

FIG. 10 shows a perspective enlarged detailed illustration of the rearpart of the tensioning device S with the roller 51 and ramp 52 of amodification of the administering device 1 according to the inventionwith just one cylinder-piston arrangement;

FIG. 11A shows a diagram for illustrating the profile of the ramp track53, wherein the angle of rotation is plotted along the x axis and thestroke along the longitudinal axis of the piston rod 36 is plotted alongthe y axis,

FIG. 11B shows a diagram for illustrating the modified profile of theramp track 53, wherein the angle of rotation is plotted along the x axisand the stroke along the longitudinal axis of the piston rod 36 isplotted along the y axis,

FIG. 12 shows a perspective illustration of the roller 51;

FIG. 13 shows a top view of the roller 51;

FIGS. 14 and 15 show perspective illustrations of the receiving block10;

FIG. 16 shows a top view of the receiving block 10, and

FIG. 17 shows a sectional view of the receiving block 10.

In the exemplary embodiment shown in FIG. 1, the device 1 according tothe invention for administering a fluid (for example a liquid) comprisesa housing 2 which comprises a base 3, which can also be in the form of astanding base 3, a gripping portion 4 for holding the device 1, atrigger 5 which is arranged in the gripping portion 4 and is intendedfor actuating the device 1, a head region 6 with a dispensing region 7,and a receptacle 8 in the upper end of the head region 6.

In the exemplary embodiment described here, the device 1 according tothe invention, which may also be referred to as the administering device1, is designed for simultaneously administering two different drugs inanimals, wherein the administration of the drug is carried out throughthe skin without needles.

In the case of the administering device 1 according to the invention, aseparate cylinder-piston arrangement is provided for each medication, aswill also be described in detail below, said cylinder-piston arrangementbeing in each case in the form of a type of self-filling device in sucha manner that a movement of the piston toward the dispensing end causesthe fluid to be injected and an opposite movement of the piston causesfilling of the cylinder for the next injection operation.

As can be inferred from the schematic sectional illustration of theadministering device 1 in FIG. 2, the administering device 1 comprises areceiving block 10 which bears a control board 11 and a motor 12, andtwo front assemblies 13, 14, of which only the front assembly 13 isvisible in the illustration of FIG. 2. Since the front assemblies 13 and14 are constructed identically, essentially only the front assembly 13will be described in detail below. A medication container M containing aliquid drug for the front assembly 13 is shown schematically in thereceptacle 8.

A sectional illustration of the front assembly 13 is shown in FIG. 3.The front assembly 13 comprises an insert 15 in which a syringe cylinder16 with an open dispensing end 17 is formed. A nonreturn valve 18 (or anintake valve 18) is arranged on the outlet side at the open dispensingend 17. When the nonreturn valve 18 is opened, the open dispensing end17 leads into a nozzle 18 via which the fluid to be dispensed (here thecorresponding liquid drug) is dispensed.

The nonreturn valve 18 is pretensioned via a spring 20 toward the opendispensing end 17 and closes the open dispensing end 17 in the positionof the nonreturn valve 18 that is shown in FIG. 3.

Furthermore, the front assembly 13 comprises a triggering cage 21 whichextends over the nozzle 19, is pressed by means of a spring 22 in thedirection from the open dispensing end 17 toward the nozzle 19 and ispretensioned. The triggering cage 21 is mounted displaceably along thelongitudinal axis of the front assembly 13 (from the left to the rightin FIG. 3), and therefore, when the administering device 1 is placedonto the corresponding skin site of the animal, said triggering cage isdisplaced in the direction from the nozzle 19 toward the open dispensingend 17 and, in the process, triggers, for example, a contact sensor (notshown) which enables the triggering of the administering operation, aswill also be described in detail below.

The insert 15 has radially running supply channels 25 at a proximal end24 of the syringe cylinder 16 lying opposite the open dispensing end 17,via which supply channels the fluid to be administered or the liquiddrug passes into the syringe cylinder 16 for a next injection operation.

An external thread 27 is formed, and a guide bushing 28 arranged, at theproximal end 26 of the front assembly 13, and therefore the frontassembly 13 can be screwed into a distal end 30 of the receiving block10 (FIG. 4) since an internal thread 31 for the external thread 27 ofthe front assembly 13 is provided in the distal end 30. FIG. 4 shows thefront assembly 13 and the distal end 30 of the receiving block 10 priorto the screwing-in operation. In FIG. 5, the two elements 13, 30 arescrewed to each other such that a piston rod 35 which is guided in thereceiving block 10 slightly protrudes with a piston 36 formed at itsdistal end into the syringe cylinder 16, and the piston rod 35 is guidedthrough the guide bushing 28. As will be described in detail below, thepiston rod 35 can be moved from the basic position shown in FIG. 5 inthe direction toward the open dispensing end 17 to the injection ordispensing position shown in FIG. 6 and from said position back againinto the basic position shown in FIG. 5.

If the piston rod 35 is in the basic position, its distal end andtherefore the piston 36 is in its rear end position (FIG. 5). When thepiston rod 35 is in the dispensing position, the piston 36 is in itsfront end position (FIG. 6).

When the piston rod 35 is positioned in the basic position shown in FIG.5, the syringe cylinder 16 is filled with the liquid drug to beinjected. A movement of the piston rod 35 toward the open dispensing end17 then leads to the nonreturn valve 18 opening and thus to the liquidbeing dispensed via the nozzle 19 as a jet which cuts into the skin ofthe animal to an extent such that the drug can be administered into theskin through said cut.

During the rearward movement from the dispensing position shown in FIG.6 to the basic position shown in FIG. 5 (a movement along a firstdirection), the nonreturn valve 18 closes and a negative pressure isproduced in the syringe cylinder 16, said negative pressure beinggreater the further the piston rod 35 is moved away from the opendispensing end 17. As soon as the piston rod 35 is brought into itsbasic position, there is a fluid connection between the syringe cylinder16 and at least one of the supply channels 25. In order to realize thefluid connection, an axial blind hole 37 is formed in the distal end ofthe piston 36 and at least one transverse bore 38 is formed whichextends radially from the blind bore 37 and the end of which that facesaway from the blind bore 37 leads into one of the supply channels 25.Since the supply channels 25 for their part lead into a chamber 32 whichis formed between the insert 15 and the distal end 30 of the receivingblock 10 and is connected via a connection element 33 to the medicationcontainer M, only shown in FIG. 2, the liquid drug because of thenegative pressure present in the syringe cylinder 16 is sucked out ofthe medication container M via the connection element 33, the chamber32, the supply channel or supply channels 25, the transverse bore(s) 38and the blind bore 37 into the syringe cylinder 16 such that the latteris filled with the liquid drug. Therefore, the drug can be administeredagain during the next triggering operation, wherein, at the beginning ofthe movement of the piston rod 35 from the basic position to theinjection position, some of the liquid drug is pressed back into thechamber 32 via the supply channels 25. This pressing back isadvantageous since the piston 36 or the piston rod 35 can thereby beaccelerated more easily, which leads to a higher pressure with which therest of the drug in the syringe cylinder 16 is acted upon and which isdesirable for the described injection without a needle.

The front assembly 13 which in particular comprises the syringe cylinder16, the nonreturn valve 18 and the nozzle 19 is designed to beexchangeable as a whole. It can be screwed by means of its externalthread 27 into, and unscrewed again from, the corresponding internalthread 31 which is formed at the distal end 30 of the receiving block10. Since the front assembly 13 is subject to wear during operation ofthe administering device 1, a worn front assembly 13 can therefore beeasily exchanged for a new, structurally identical front assembly 13.This advantageously leads to the administering device 1 as a whole beingable to be used for longer since the components of the administeringdevice 1 that are most susceptible to wear can be easily exchanged.

Since the front assembly 13 can be completely exchanged, undesirablecontaminations can be reliably avoided, which would be significantlymore difficult to avoid and would be associated with higher costs if,for example, the firstly wearing O-ring seals in the administeringdevices known from the art were individually exchanged in the region ofthe cylinder which is connected fixedly and nonexchangeably to the restof the device known from the art.

As can best be seen from FIGS. 7 to 9, the receiving block 10 has afirst receiving cylinder 40, into which the piston rod 35 for the firstfront assembly 13 is guided, and a second receiving cylinder 140, inwhich a piston rod 135 for the second front assembly 14 is guided. Sincethe construction of the two cylinder-piston arrangements and thereforeof the two receiving cylinders 40, 140 is identical, essentially onlythe first cylinder-piston arrangement with the first receiving cylinder40 will be described below in the description of the receiving block 10.Corresponding elements in the case of the second receiving cylinder 140are denoted by reference signs which are greater by 100 than in the caseof the elements of the first receiving cylinder 40, but will not bedescribed once again.

The piston rod 35 runs through the first receiving cylinder 40 in whicha spring 41 for moving the piston rod 35 from the tensioned basicposition shown in FIG. 5 to the injection position shown in FIG. 6 iscontained. A distal end 42 of the spring 41 lies against a stop portion43 of the piston rod 35. The proximal end 44 of the spring 41 liesagainst a guide bushing 45 which is screwed into the proximal end of thefirst receiving cylinder 40, and therefore, during a movement of thepiston rod from the injection position shown in FIG. 6 along the firstdirection to the pretensioned basic position shown in FIG. 5, the spring41 is compressed and is thereby pretensioned, as is illustrated in FIG.9.

As can be gathered in particular from the enlarged perspectiveillustration in FIG. 10, that end of the piston rod 35 which protrudesproximally out of the receiving cylinder 40 is connected to a driver 50which has a rotatably mounted roller 51, wherein the axis of rotation ofthe roller 51 extends substantially perpendicularly to the longitudinalaxis of the piston rod 35.

The perspective illustration in FIG. 10 shows a modification of theadministering device 1 according to the invention. In this modification,only a single cylinder-piston arrangement is formed, and the driver 50is connected to the proximal end of the piston rod 35 and to theproximal end of a guide rod 39, which is mounted displaceably in thereceiving block 10.

The roller 51 runs on a ramp 52 which rotates under the roller 51 and isrotated by the motor 12 about an axis parallel to the longitudinal axisof the piston rod 35. A battery and/or a storage battery which can berecharged is provided as current supply for the motor. The batteryand/or the storage battery can be arranged, for example, in the base 3or as the base 3 of the administering device 1.

The ramp 52 has a ramp track 53 which runs with a single turn along ahelical line, as can be gathered in particular from FIGS. 7, 8 and 10.

In FIG. 11A, the angle of rotation α is plotted in relation to the pitchdifference z parallel to the longitudinal direction of the piston rod35, wherein the starting point is that, at the angle of rotation ofα0=0°, the smallest pitch height z0 is present and the piston 36 is inits front end position. If the ramp 52 is then rotated, the ramp track53 runs under the roller 51 and leads to the rotational movement of theramp track 53 being converted into a translatory movement of the roller51 together with the driver 50 and therefore the piston rod 35 along thelongitudinal axis of the piston rod 35, such that the piston rod 35 ismoved from its injection position shown in FIG. 6 into its basicposition shown in FIG. 5.

For this purpose, the unwound ramp track 53 according to FIG. 11A runsin such a manner that there is a first plateau (inclination=0 or onlysomewhat greater or somewhat less than zero) from the angle of rotationα0 to an angle of rotation α1. From the angle of rotation α1, the ramptrack 53 has a first linear inclination portion S1 which is present asfar as the angle of rotation α2. At the angle of rotation α2 (and thecorresponding pitch height z1), the pitch merges into a second linearinclination portion S2 which has a greater inclination than the firstlinear inclination portion S1 (between the angles of rotation α1 andα2). The second inclination is present as far as the angle of rotationα3 and then merges into a second plateau in which the pitch height z2does not increase (or only increases very slightly or only decreasesvery slightly) in the event of a further increase in the angle ofrotation as far as the angle of rotation α4 of less than 360°.

At the angle of rotation α5, an edge 54 is formed because of thetransition flank 46 which connects the second plateau to the firstplateau.

In the region from α3 to α4, the piston rod 35 is in its tensioned basicposition according to FIG. 5. The administering device 1 is thereforeready for the application of the liquid drug.

If the trigger 5 is then actuated and the triggering cage 21 is in thetriggering position, the motor 12 rotates the ramp 52 further such that,when the angle of rotation α5 is exceeded, the roller 51 runs over theedge 54 and, because of the tensioning of the spring 41, drops abruptlyback from the pitch height z2 to the pitch height z0 of the firstplateau, and therefore the fluid present in the syringe cylinder 16 isinjected in the described manner.

The motor 12 then rotates the ramp 52 further as far as the secondplateau and stops the rotational movement here such that the syringecylinder 16 is thereby again filled with the liquid drug and the pistonrod 35 is brought again into its tensioned basic position. Theadministering device 1 is therefore provided for a further administeringoperation. The administering device 1 can thereby be repeatedly wound upand triggered.

The two inclination portions S1 and S2 form a region of inclinationwhich runs from the first plateau as far as the second plateau. The twoinclination portions S1 and S2 do not have to run linearly with respectto the angle of rotation. As is shown by way of example in FIG. 11B,they can also have a concave curvature (at which the local inclinationincreases as the angle of rotation increases). However, even in thiscase, the average inclination of the first inclination portion S1 issmaller than the average inclination of the second inclination portionS2.

The combination of motor 12, ramp 52, driver 50 with roller 51, spring41, 141 and guide bushing 45, 145 can be referred to as the tensioningdevice S.

As can be gathered in particular from FIGS. 12 and 13, the roller 51comprises a central region 55 which has a constant outside diameter.This is adjoined on both sides by a respective side region 56, 57 inwhich the outside diameter decreases toward the side.

The two side regions 56 and 57 are each adjoined by an end region 58, 59which is rounded so that the roller 51 does not have any edges. Uponrotation of the ramp 52, the central region 55 lies on the ramp track 53in the rotational angle region of α1 to α3 (in particular of α0 to α5)whereas the side regions 56 and 57 do not rest in said rotational angleregion, but rather come into contact with the ramp track 53 only onrunning over the edge 54. The rolling resistance of the roller 51 duringthe tensioning of the piston rod 35 (rotation of the ramp track from thefirst to the second plateau) can therefore be as small as possible.During the transfer from the second or upper plateau (rotational angleregion α3 to α4) of the ramp track 53 to the lower plateau (rotationalangle region α1 to α2), the side regions 56 and 57 are also in contactwith the edge 54, as a result of which the forces between the roller 51and the edge 54 of the ramp track 52 are advantageously distributed overa greater support surface (central region 55 and the two side regions56, 57), and therefore a smaller pressure is present. The durability ofthe device 1 and in particular of the roller 51 is thereby increased.

The characteristics of the inclination of the ramp track 53 described inconjunction with FIGS. 11A and 11B are advantageous since, at thebeginning (rotational angle region α1 to α2), there is a smallerinclination, and therefore less torque has to be provided by the motor50. This is of advantage precisely during the starting of the motor 50from the first plateau since the motor 50 customarily draws more currentin this region. When the pitch height z1 is reached, the higherinclination in the rotational angle region from α2 to α3 can easily beovercome by the motor 50.

These characteristics of the inclination of the ramp track 52advantageously lead to the durability of the motor 50 being increased.

As can best be gathered from the illustrations from FIGS. 14 to 17, thereceiving block 10 is formed integrally. Here, for example, use has beenmade of an additive production method, such as, for example, lasersintering, selective laser sintering or direct metal laser sintering,with which finer and/or more complex structures can be produced incomparison to machining methods. The receiving block 10 can therefore beprovided with a relatively low weight and it can be ensured that theadministering device 1 is highly durable.

Examples of the material used for the receiving block 10 can includealuminum, steel (for example maraging steel), stainless steel, titanium,a nickel alloy and/or a cobalt chromium alloy. The material for thelaser sintering here is preferably in the form of metal powder. For theadditive or layered production of the receiving block 10, a thin layerof the powder material can be applied to a construction platform. Alaser beam melts the powder exactly at the points which arepredetermined by computer-generated component design data of thereceiving block 10. The construction platform is then lowered, and afurther thin layer of the powder material is applied. The material ismelted again and binds at the defined points to the layer lyingtherebelow. These steps are repeated until the entire receiving block 10is formed.

In addition to the receiving cylinders 40, 140 already described, thereceiving block 10 comprises four board receiving points 60, 61, 62 and63, onto which the board 11 can be placed and, for example, screwed tothe receiving block 10.

Furthermore, the receiving block comprises a motor bearing 64 forreceiving and mounting the motor 12.

Furthermore, four fixation points 65, 66, 67 and 68 are formed for theouter housing 2 of the administering device 1. Portions of correspondingreceptacles 265, 266, 267 and 268 of the outer housing 2 are shown inFIGS. 7 to 9.

At the distal end of the receiving block 10, the umbrella-likedispensing region 7 is provided which, in addition to the correspondinginternal thread 31 and 131 for the first and second front assembly 13and 14, also has receptacles 69 and 169 for the respective triggeringsensor (not shown) that detects the position of the triggering cage 21,121.

Furthermore, an O-ring receptacle 70, into which an O-ring 71 (forexample FIGS. 9, 16 and 17) can be inserted, is formed in the dispensingregion 7 in order to ensure sealing in relation to the adjacent housing2 in the installed state.

Furthermore, the receiving block 10 for each receiving cylinder 40, 140comprises a receptacle 72, 172, into which the corresponding connectionelement 33, 133, which can also be referred to as a fluid adapter, canbe inserted.

The connection element 33, 133 is preferably produced by machining.

Titanium is preferably used as the material for the receiving block 10.This material is firstly relatively light and secondly ensures thedesired strength. Of course, any other suitable material for additiveproduction methods may be used.

The description above has been based on the intention of simultaneouslyadministering two different medications. However, the administeringdevice 1 according to the invention may also be designed in such amanner that the receiving block 10 has only one individual receivingcylinder 40, and therefore also only one single medication can beadministered during a triggering operation. The second receivingcylinder 140 and the second cylinder-piston rod combination are thenpreferably omitted.

The previously described exemplary embodiments have been based on theadministering device 1 being in the form of an administering device 1without needles. However, it may also be in the form of an administeringdevice 1 with a needle or a canula, and therefore, in this case, theneedle or canula is intended to pierce the skin of the animal and thenthe application of the liquid drug takes place in the described manner.

1. A device for administering a fluid, comprising a cylinder (16, 116)which has an open dispensing end (17), a piston (36) which isdisplaceable between a front and rear end position in the cylinder (16,116) and is connected to a plunger rod (35) that protrudes along a firstdirection beyond a rear end of the cylinder (16, 116) opposite the opendispensing end (17) and is guided in a receiving block (10), a nonreturnvalve (18) closing the open dispensing end (17), and a tension device(S) which is connected to the piston rod (35, 135) and is arranged inthe receiving block (10), wherein the tensioning device (S), when thepiston (36) is in its front end position, can move the piston rod (35,135) in a tensioning operation along the first direction until thepiston (36) is in its rear end position in order thereby to fill thecylinder (16, 116) with the fluid to be administered and in order topretension the piston rod (35, 135) toward the open dispensing end (17),and wherein the tensioning device (S), when the piston (36) is in itsrear end position, can release the piston rod (35, 135) in a dispensingoperation, and therefore the piston (36) moves counter to the firstdirection as far as its front end position because of the appliedpretension and, in the process, fluid in the cylinder (16, 116) isdispensed via the nonreturn valve (18) for administering, wherein thecylinder (16, 116) together with the nonreturn valve (18) is in the formof an exchangeable front assembly (13, 14) which is releasably connectedto the receiving block (10).
 2. The device as claimed in claim 1,wherein the releasable connection between the front assembly (13, 14)and the receiving block (10) is a screw connection.
 3. The device asclaimed in claim 1, wherein the device has a nozzle (19) foradministering the fluid without a needle, said nozzle being connected tothe open dispensing end of the cylinder (16, 116) via the nonreturnvalve (18) and being part of the front assembly (13, 14).
 4. The deviceof claim 1, wherein the tensioning device (S) has a spring (41, 141)which pretensions the piston rod (35, 135) toward the open dispensingend when the piston (36) is in the rear end position.
 5. The device ofclaim 1, wherein the tensioning device (S) has a ramp (52) which isrotatable by means of a motor (12) and has a ramp track (53) extendingalong a helical line, wherein the ramp track (53) ascends from a firstplateau along a region of inclination (S1, S2) to a second plateau anddescends from the second plateau to the first plateau via a transitionflank (46), wherein the tensioning device (S) furthermore has a roller(51) which is in contact with the ramp track (53) and is mountedrotatably in a driver (50), which is connected to that end of the pistonrod (35, 135) which protrudes out of the cylinder (16, 116), andtherefore, upon rotation of the ramp (52), the ramp track (53) runsbelow the roller (51), which thereby rotates, wherein, for thetensioning operation, the ramp track (53), starting from a contact ofthe roller (51) with the first plateau, is rotated in such a manner thatthe roller (51) runs on the region of inclination as far as the secondplateau and the piston (36) is thereby moved into its rear end position,wherein, for the dispensing operation, the ramp track (53), startingfrom a contact of the roller (51) with the second plateau, is rotateduntil the roller (51) via the transition flank (46) reaches the firstplateau and the piston (36) is thereby moved into its front endposition.
 6. The device as claimed in claim 5, wherein the motor (12) ismounted in the receiving block (10).
 7. The device as claimed in claim5, wherein the region of inclination of the ramp track (53) has a firstportion (S1) adjoining the first plateau and an adjoining second portion(S2), wherein the inclination of the second portion (S2) is greater thanthe inclination of the first portion (S1).
 8. The device as claimed inclaim 7, wherein both portions (S1, S2) run linearly with respect to theangle of rotation of the helical line.
 9. The device as claimed in claim6, wherein the length of the angle of rotation of the first portion (S1)is smaller than the length of the angle of rotation of the secondportion (S2).
 10. The device as claimed in claim 5, wherein the roller(51) has a support region (55) which rests on the region of inclination(S1, S2) of the ramp track (53), and at least one laterally adjoiningside region (56, 57) which has a smaller outside diameter than thesupport region (55) and which does not rest on the region of inclination(S1, S2) of the ramp track (53), wherein, during the dispensingoperation, both the support region (55) and the side region (56, 57)come into contact with an edge (54) of the ramp track (53), said edgeconnecting the second plateau to the transition flank (46).
 11. Thedevice as claimed in claim 10, wherein the roller (51) on either side ofthe support region (55) has a laterally adjoining side region (56, 57)with a smaller outside diameter than that of the support region (55).12. The device as claimed in claim 10, wherein the outside diameter ofthe respective side region (56, 57) decreases in a direction toward theside of the roller (51).
 13. The device as claimed in claim 5, whereinthe roller (51) is mounted in the driver (50) in such a manner that theaxis of rotation of said roller is perpendicular to the first direction.14. The device of claim 1, in which the receiving block (10) is in theform of an integral receiving block (10) which is produced by anadditive production method.
 15. The device as claimed in claim 14,wherein the receiving block (10) is in the form of a metal receivingblock (10).
 16. The device as claimed in claim 14, wherein the receivingblock (10) has a motor bearing (64), a guide cylinder (40, 140) for thepiston rod (35, 135), at least one receptacle (60, 61, 62, 63) for acontrol board (11), a receptacle (72, 172) for a fluid connection (33)for a fluid container (M) and/or at least one housing fixing point (65,66, 67, 68), which are/is formed integrally with the receiving block(10).